// Maps are Go's built-in associative data type (sometimes
// called "hashes" or "dicts" in other languages).

package main

import "fmt"

func main() {
    // To create an empty map, use the builtin `make`:
    // `make(map[key-type]val-type)`.
    m := make(map[string]int)

    // Set key/value pairs using typical `name[key] = val`
    // syntax.
    m["k1"] = 7
    m["k2"] = 13

    // Printing a map with e.g. `Println` will show all of
    // its key/value pairs, which can be useful for
    // debugging.
    fmt.Println("map:", m)

    // Get a value for a key with `name[key]`.
    v1 := m["k1"]
    fmt.Println("v1: ", v1)

    // The builtin `len` function returns the number of
    // key/value pairs when called on a map.
    fmt.Println("len:", len(m))

    // The builtin `delete` removes key/value pairs from
    // a map
    delete(m, "k2")
    fmt.Println("map:", m)

    // The optional second return value when getting a
    // value from a map indiciates if the key was present
    // in the map. This can be used to disambiguate
    // between missing keys and keys with zero values
    // like `0` or `""`.
    _, prs := m["k2"]
    fmt.Println("prs:", prs)
}